Enicognathus Leptorhynchus) in a Fragmented Agricultural Landscape of Southern Chile Ana Paula B
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The Condor 114(1):166–172 © The Cooper Ornithological Society 2012 POST-FLEDGING HABITAT SELECTION BY THE SLENDER-BILLED PARAKEET (ENICOGNATHUS LEPTORHYNCHUS) IN A FRAGMENTED AGRICULTURAL LANDSCAPE OF SOUTHERN CHILE ANA PAULA B. CARNEIRO1,5, JAIME E. JIMÉNEZ2,3, AND THOMAS H. WHITE JR.4 1Laboratorio de Vida Silvestre, Universidad de Los Lagos, Avenida Fuchslocher 1305, Osorno, Chile 2Sub-Antarctic Biocultural Conservation Program, Department of Biology and Department of Philosophy and Religion Studies, University of North Texas, Denton, TX 76203-5017 3Omora Ethnobotanical Park, Universidad de Magallanes, Puerto Williams, Chile 4U.S. Fish and Wildlife Service, Puerto Rican Parrot Recovery Program, Box 1600, Rio Grande, Puerto Rico 00745 Abstract. Despite the importance of the post-fledging period in avian population dynamics, little is known about habitat use during this life stage. We examined habitat selection by radio-tracked juvenile Slender-billed Parakeets (Enicognathus leptorhynchus) at multiple spatial scales in a fragmented agricultural landscape of south- ern Chile. Using home ranges versus study area (home-range selection) and locations versus combined home range (habitat-type selection), we based spatial analyses of habitat selection on the population level. Slender-billed Parakeets made similar habitat choices across the hierarchical levels examined, except for riparian and native second-growth forests, which they avoided at the level of overall home-range selection but used in proportion to availability at the level of habitat-type selection. Farmland and pastures with high densities of scattered mature trees were the only habitats positively selected at multiple spatial scales, adding to the increasing amount of lit- erature highlighting the value of such trees for native fauna in highly modified areas. These trees appeared to be important for the birds during the post-fledging period as sites for feeding, perching, and roosting and to facilitate movement through open agricultural landscapes. Key words: agricultural landscapes, habitat use, post-fledging, radio-tracking, Slender-billed Parakeet, Enicognathus leptorhynchus. Selección de Hábitat por Enicognathus leptorhynchus en un Paisaje Agrícola Fragmentado en el Sur de Chile Durante el Período Posterior al Abandono de los Nidos Resumen. A pesar de la importancia del período posterior al abandono de los nidos en la dinámica poblacional de las aves, poco se sabe sobre el uso de hábitats durante esta etapa. El propósito de este estudio fue examinar la selección de hábitats por juveniles de Enicognathus leptorhynchus, mediante radio-telemetría, a múltiples escalas espaciales en un paisaje agrícola fragmentado en el sur de Chile. Los análisis espaciales de selección se basaron en el ámbito de hogar versus el área de estudio (selección del ámbito de hogar) y en las localizaciones versus los ámbi- tos de hogar combinados (selección del hábitat) a nivel poblacional. La selección de hábitats por E. leptorhynchus fue similar para los distintos niveles jerárquicos propuestos en el presente estudio, excepto por las áreas ribereñas y los bosques nativos secundarios que fueron evitados cuando los ámbitos de hogar fueron comparados con el área de estudio, y fueron utilizadas de acuerdo a su disponibilidad cuando las localizaciones se compararon con los ámbitos de hogar combinados. Las matrices agrìcolas que tenían mayores densidades de árboles aislados fueron los únicos hábitats seleccionados positivamente en múltiples escalas espaciales, concordando con la creciente literatura que destaca la importancia de estos elementos para la fauna nativa en ambientes altamente modificados. Estos árboles parecen ser importantes para el período posterior al abandono de los nidos, ya que son usados como fuentes de alimentación, sitios para descansar y dormideros, y para facilitar el desplazamiento a través del paisaje. INTRODUCTION and predation risks (Luck 2002, Brandt and Cresswell 2008, Animals are usually distributed nonuniformly through their Harvey et al. 2008). Hence, habitat selection results from a range (Marzluff et al. 2004, Harvey et al. 2008). Often they hierarchical process of behavioral responses involving a dispro- use habitats according to a combination of factors including portionate use or avoidance of some habitat types in relation to resource availability, life-history strategies, dispersal abilities, their availability (Thomas and Taylor 2006, Aarts et al. 2008). Manuscript received 5 July 2010; accepted 22 June 2011. 5E-mail: [email protected] The Condor, Vol. 113, Number 1, pages 166–172. ISSN 0010-5422, electronic ISSN 1938-5422. © 2012 by The Cooper Ornithological Society. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press’s Rights and Permissions website, http://www.ucpressjournals.com/ reprintInfo.asp. DOI: 10.1525/cond.2011.100127 166 POST-FLEDGING HABITAT SELECTION BY ENICOGNATHUS LEPTORHYNCHUS 167 Ideally, the most effective way to conserve animal pop- period and attributes such as home-range size, habitat-use pat- ulations is by protecting habitats upon which these popula- terns, and habitat selection have remained unknown. Despite tions depend (Petit et al. 1999, Brandt and Cresswell 2008, being legally protected in Chile, the Slender-billed Parakeet is Lagory et al. 2009). To be effective, however, conservation nevertheless highly persecuted by farmers because of its per- requires the protection of critical resources through all life ceived damage to agricultural crops and orchards (Carneiro stages (Ciudad et al. 2009). Although juvenile survival and 2010). The purpose of our study was to examine habitat se- dispersal can have important effects on population dynam- lection by radio-tracked juvenile Slender-billed Parakeets at ics, the post-fledging period is perhaps the least studied and multiple spatial scales in a fragmented agricultural landscape least understood part of the avian life cycle (Kershner et al. of southern Chile. We based our analyses of habitat selection 2004, Salinas-Melgoza and Renton 2007, Whittaker and Mar- on the population-level second and third hierarchical orders zluff 2009). The few studies that have examined habitat use proposed by Johnson (1980). Our fundamental objective was by juvenile birds during the post-fledging period suggest that to obtain baseline ecological data on a bird heretofore poorly habitat use is influenced mainly by food supply and foraging known, data that could be a base not only for recommenda- conditions (e.g., Ciudad et al. 2009, Mitchell et al. 2009). tions of specific conservation measures but also for species- Beyond the importance of understanding habitat re- specific research priorities. quirements at various life stages, there is ample evidence that studies addressing only one spatial scale are inherently lim- METHODS ited (Luck 2002, Beasley et al. 2007, Ciudad et al. 2009), be- cause habitat-use patterns, particularly those in fragmented STUDY AREA landscapes, are influenced by ecological processes occurring We studied Slender-billed Parakeets within 520 km2 of frag- at multiple spatial scales (Li et al. 2006, White et al. 2006, mented landscape devoted to agriculture and livestock graz- Bayley and Thompson 2007, Manning et al. 2007, Vergara ing in the central valley of the Lakes Region, southern Chile, and Armesto 2009). Johnson (1980) suggested four levels of 12 km south of the city of Osorno (40° 55′ S, 73° 35′ W). The habitat selection associated with scale-dependent habitat use, climate is cool wet-temperate (sensu Holdridge 1967) with a reflecting resource use by species across multiple hierarchi- strong oceanic influence (Echeverría et al. 2007). Rainfall is cally nested spatial scales (Ciarniello et al. 2007, Lagory et evenly distributed throughout the year, with a slight reduction al. 2009). These hierarchical orders of selection are defined during the austral summer (December– February). Average as selection within the geographical range of the species (first yearly precipitation is 1383 mm, and the mean temperature is order), selection of a home range by an individual or social 11.4 °C (Luebert and Pliscoff 2006). group within the landscape (second order), selection of habi- Historically, the region was covered by continuous tat types within the home range (third order), and selection of deciduous lowland forest dominated by the trees Nothofagus a specific resource, such as a nest site (fourth order) (Johnson obliqua, Laurelia sempervirens, and Persea lingue (Donoso 1980, Li et al. 2006, Ciarniello et al. 2007, Lagory et al. 2009). 1993, Luebert and Pliscoff 2006). However, intensive logging Therefore, optimal conservation strategies should consider and anthropogenic fires have shaped the landscape for at habitat selection through all life stages and at multiple spatial least the past 100–150 years (Castellón and Sieving 2006, scales. Echeverría et al. 2007, Vergara and Armesto 2009). The Although multitudes of animal populations are declining current landscape is a mosaic of small patches of secondary worldwide because of anthropogenic destruction and altera- forest and plantations of exotic trees surrounded by extensive tion of their habitats (Petit et al. 1999, Virkkala et al. 2004, areas of farmland and pastures (Fig. 1) with numerous mature Carter et al. 2006), for many such species there is a lack of N. obliqua and L. sempervirens scattered throughout. basic ecological information on